Process of utilizing old paper stock



April 1927' J. E. PLUMSTEAD PROCESS OF UTILIZING OLD PAPER STOCK Filed June 21, 1926 0L0 PAPER MACERA T OR' D/GES TER on SHREDDER 77q/vK FOR BLOW 4 MACERA TED TAN K SHREDD E D 0L 0 PA PER WASH/N6 APPARATUS UsuA L ROOT/NE l nueni'or:

ALAOIMM Q Patented Apr. 19, 1927.

UNITED STATES JOSEPH E. PLUMSTEAD, OF WILMINGTON, DELAWARE, ASSIGNOR TO THE JESSUP 8:

PATENT OFFICE.

MOORE PAPER (10., OF PHILADELPHIA, PENNSYLVANIA, A CORPORATION OF MASSACHUSETTS.

PROCESS OF UTILIZING OLD PAPER STOCK.

Application filed June 21,

This invention relates to a method of producing chemically cooked pulp for use in paper making.

The invention is specifically concerned with the utilization of old paper stock and paper shavings by mixing the same with new cellulosic material for the production of good pulp without the necessity of individually cooking the old paper stock.

To this end the invention consists in mechanically disintegrating or macerating old paper stock in water preferably made alkaline and then introducing this wet macerated mass into a tank which contains a hot charge of chemically cooked pulp from a digester.

The latent heat of the pulp blown from the digester has been found to be sufiicient to thoroughly cook the macerated used pulp stock added thereto. The presence in this blow-tank of those amounts of cooking liquor normally occurring unused in the finished charge from a digester has been found to be suflicient to de-ink and completely disintegrate the used stock so that it is then in a proper condition to be bleached and finished. V

I have illustrated diagrammatically in the accompanying drawing the ordinary ste s taken in the treatment of chemical pu p which steps are indicated in light lines and in heavy lines I have indicated the point at which this old stock is to be introduced into the system and the treatment accorded the stock before such introduction.

5 The used paper stock above referred to may be of any grade or quality dependin upon the quality of pulp which it is desire to produce as an end product.

This old stock may be disintegrated in any 0 desired type of mechanical macerater.

The preliminary disintegrating process may be carried out in the cold and no heat is necessary as it is well known that heat is not essential for the disintegration of paper fibres.

A hot charge from a digester is then blown into a suitable tank orreceptacle to which tank has been added the macerated 1926. Serial No. 117,483.

stock. It has been found that in order to completely agitate and mix the two batches, it is desirable to first run into the blow-tank the cold macerated stock so that the hot charge from the digester will stir the two masses as it enters the tank.

The latent heat in this hot digester charge has been found sufficient to thoroughly cook the used stock and to separate the cellulosic fibres from any undesirable material contained therein. At the same time, the presence of normally occurring unused portions of the cooking liquor are suflicient to de-ink and actually cook this used material.

This mixed mass is then put through the usual steps of the process leading to the production of the final pulp which includes drainage and washing to free the pulp from black liquor and ink residues and the subsequent bleaching and other steps as is well known in the art.

Having thus described the invention, what I claim as new is: i

1-. A method of cooking paper stock which consists in the step of disintegrating the same in a relatively cold state and then mixing this disintegrated stock with a hot charge of chemically cooked pulp and producing finished pulp from this mixed mass.

2. A method of cooking aper stock which consists in mechanically isintegrating the same while wet and in a relatively cold state in an alkaline suspension and mixing this batlch with a hot charge of chemically cooked pu p.

3. A method of producing chemical pulp which consists in chemically cooking under heat and pressure a charge of cellulosic containing material blowing this charge into a suitable receptacle, separately mechanically disintegrating a batch of old 'stock while wet and relatively cold and mixing the hot and the cold batches whereby the old stock is thoroughly cooked andthe cellulosic fibres separated from the undesirable material.

In testimony whereof I-aflix my signature.

JOSEPH E. PLUMSTEAD. 

